Lists of Common Words
These lists of high-frequency words are drawn from various sources, and mainly based up a national corpus (British or American). A corpus is a collection of texts and recorded speech consisting of tens of millions of words. From such a large volume of data, it is possible to calculate the frequency with which words occur in a language. Inevitably, not all corpuses are identical or agree with one another, and you may notice minor differences in frequency or rank within these lists. Such differences are insignificant.